Coded ink recording and reading



Dec. 23, 1969 A, S GEL 3,486,006

CODED INK RECQRDING AND READING Filed Feb. 9. 1966 2 Sheets-Sheet 1INVENTOR. LESTER AARON S/EGEL ATTORNEY Dec. 23, 1969 Filed Feb. 9, 1966L. A. SIEGEL CODED INK RECORDING AND READING 2 Sheets-Sheet /n .L. 1 l w2/- m PAPER INVENTOR.

LESTER AARON .SIEGEL United States Patent U.S. Cl. 23561.11 3 ClaimsABSTRACT OF THE DISCLOSURE A typewriter or similar machine is providedwith a ribbon having horizontal zones each zone having an ink containinga single photoluminescent or other color selective component of a codewhich is different from that of every other horizontal zone in theribbon. Code hammers, either arranged on a type bar or a single headwith controllable hammers, strike through the particular ribbon zonescorresponding to the code for the letter or other symbol on thetypewriter keyboard. This results in printing a series of small,vertically spaced marks corresponding to the code. If desired anadditional zone of the ribbon may have ordinary ink and a type bar mayalso have a shaped symbol that strikes this zone. Readout is bysimultaneous illumination of all of the code marks by ultraviolet lightor if there are some code marks which are visible colors by successiveillumination with ultraviolet light and then with visible light. As thewhole of the code marking area is illuminated at the same time theproblem of misalignment in readout is eliminated.

SUMMARYOF THE INVENTION This application is concerned with a method ofcoding characters or symbols by means of a number of photoluminescentmaterials, including preferably chelates of lanthanide ions. The symbolsor characters involve different mixtures of one or more of thephotoluminescent components. The number of different symbols is 2 -1where n is the number of photoluminescent components, for example 15with 4 components, 63 with 6 components, and the like. Each symbol hasthe mixture of the various components corresponding to the symbol allpresent at the same time, and the symbol is read by illumination withultraviolet light, for example a mercury vapor lamp, and allowing thefluorescence produced to strike a number of detectors equal to thenumber of photoluminescent components, each one responding only to thewavelength range of the fluorescence of a single component. The chelatesof the lanthanide ions fluoresce in very narrow wavelength bands due toexcitation of the lanthanide atoms to a particular metastable state, theemission being when the atom returns to a lower state. Ordinaryfluorescent materials operate under a slightly different mechanism andhave much broader bands of fluorescence. This is why the chelatedlanthanide ions are preferred as at least part, and if desired all, ofthe photoluminescent components. In general the fluorescence band ofordinary fluorescent material, such as for example 4,5diphenylimidazolone-Z, is broad enough so that generally it is practicalto use only one ordinary fluorescer as a component in the coded symbol.

Some problems have arisen in printing the symbols on a typewriter oranalogous machine because of contamination of the mixture for one symbolwith small amounts of other mixtures which have been printed before andwhich correspond to diflerent symbols. It is with an improved printingapparatus that the present invention deals. The typewriter or analogousprinting machine is provided with a ribbon divided into zones at rightangles to the line of printed symbols for a given message. In a3,486,006 Patented Dec. 23, 1969 common type of machine, analogous to anordinary typewriter, the message is usually in a horizontal line and sothe ribbon is divided into horizontal strips or zones. For simplicity,in the remainder of the specification reference will be made tohorizontal zones, although it should be realized that it is of coursepossible to design printing machines in which the message is vertical,for example on a tape, and in such a case the directions are turnedthrough horizontal becomes vertical and vice versa. Because of the morecommon type of machine with horizontal message lines, this simplifiedterminology will be used to illustrate the invention.

Let us assume a symbol code with six photoluminescent components withfive of them chelates of different lanthanide ions and the sixth eithera chelate of a different ion or an ordinary fiuorescing material, suchas for example the diphenylimidazolone referred to above. Eachhorizontal zone or strip in the ribbon is impregnated with one componentonly and a typing bar having a vertical height of the total number ofribbon strips with projections aligning with the particular ones foreach coded symbol is used. When the key corresponding to the symbol, forexample letters of the alphabet, number digits, mathematical signs andthe like, is struck, the corresponding type bar prints through theribbon, for example a number of rectangles, corresponding to thecomponents in the coded ink. An alternative method is to have a verticalprinting head with six hammers which can be caused to project and strikethe ribbon to type the particular coded symbol or can be caused toproject from the vertical head, which then is caused to strike theribbon. Let us assume, for the sake of illustration, that a type barwith projections aligning with the second and fourth strips on theribbon is actuated and prints two tiny rectangles, one in the componentcorresponding to the second strip and one in the component correspondingto the fourth strip. For example, these strips might be impregnated witheuropium chelates and terbiu m chelates respectively.

It is important that the strips do not permit contamination of one stripwith components from another one. This usually requires a slightseparation between the strips and preferably a carbon type of ribbon isused in which the coating is solid and not liquid, as impregnated ink ina fabric is, and which ribbon is used only once through. This is thepreferred form of ribbon but of course any other form which will permitseparation of the strips, each having one of the symbol components, canbe employed.

Readout is effected by illumination with ultraviolet light andspectralanalysis or resolution of the particular bands of fluorescenceoccurring. The physical separation of the diiferent components in thepresent invention may require some modification of the optical portionof the readout when certain methods are employed. This will be set outin more detail below. In any case, the present invention presentscertain important advantages. One of the principal advantages is that agiven type bar or the portions thereof always make an impression of asingle component of the coded ink. There is no possibility ofcontamination because a key may have struck another component or mixturefor a preceding symbol and still retain some residual amounts of thiscomponent or components.

The complete separation of each component increases the reliability andsharpness of resolution of the message. If we consider any uncertaintyas the analog of noise in an electrical system we may think of thepresent invention as having the advantage of printing symbols which inreading out show a higher signal to noise ratio, always a desirablecharacteristic of any system. Ambiguities are thus minimized orcompletely eliminated and control of the whole system is rendered lesscritical.

One illustration of this advantage will suffice. When there iscontamination of components in a symbol, it may be possible to read outsatisfactorily if the radiation intensity of the ultraviolet light isvery high and the efficiency of detection and signal processing alsohigh. If the reliability or signal to noise ratio is only moderatelyadequate, reductions in illuminating power, efliciency of detection ofthe fluorescent responses and the like may drop below the level at whichprecise, unambiguous resolution results. In the case of the presentinvention, however, where there is never any contamination, the sameloss of illumination intensity or other factors affecting final responsemight still be completely adequate. It must be remembered that coded inkmessage symbols may be used under a wide number of operating conditions,some of them, for example reading numbers or messages on passing boxcars, rapidly moving checks and the like, represent conditions which arenot always as ideal as those which can be maintained in the laboratory;and therefore additional margin of safety for adequate reliability,which the present invention provides, is always a practical and usefuladvantage.

A printed symbol may have both a definite shape that can be recognizedby visual observation and the coded inks in the single symbol. Forexample, in the case of numerical and letter messages, there can beadded a black pigment, and the symbol then appears visually in itsshape. For example, the digit 2 would look like a black 2 and would alsohave the combination of components which would correspond to the samesymbol. In some cases the ability to read a message without ultravioletor other illumination and spectral analysis is of practical importance.Of course in such a case the secrecy of the message is comprised, whichwould otherwise be assured by printing only an arbitrary shape andrelying on the fluorescence of the coded ink only. The present inventionlends itself to the modification permitting reading without irradiation,for example by typing the particular symbol above or below the othersymbol strips in, for example, a black ribbon zone. In such a casestriking the keyboard of the modified typewriter or printer for aparticular symbol, for example again the member 2, would cause theproper hammers to protrude in-the coding key and also a second type keywith 2 on its face will strike above or below the coding key. Bysuitably olfsetting these other ordinary typing keys, the coding key andthe ordinary key may be struck at the same time.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an elevation insemi-diagrammatic form of a type or printing ribbon;

FIG. 2 is an enlarged representation of a portion of the ribbon with thezones more clearly separated;

FIG. 3 is an elevation of a coding printing head with six hammers;

FIG. 4 is an elevation of a type bar with the arm of the bar brokenaway;

FIG. 5 is the representation of four symbols in the form of verticalstrips, and

FIG. 6 is a diagrammatic representation of a readout mechanism for allphotoluminescent symbols.

DESCRIPTION OF THE PREFERRED EMBODIMENTS In FIG. 1 a typing or printingribbon is shown generally at 7 with the conventional spools 8 and 9. Theribbon, as can be best seen in FIG. 2, which is an enlarged view of aportion of the ribbon, is divided into six horizontal strips numbered 1to 6. Each strip is impregnated or coated with a composition containingat least one photoluminescent component. For example, strip 1 may have acompound containing 4,5-diphenyli rnidazolone-Z, and strips 2 to 6 carrychelates of various lanthanide ions.

FIG. 3 shows in diagrammatic form a printing head 10 with six hammers 11to 16 positioned to align with the ribbon strips 1 to 6 respectively andwhich are individually actuated by pressing diiferent coding keys.

FIG. 4 shows an ordinary type bar with an arm 28 and a type face whichperforms the same function as the printing head and is therefore alsonumbered 10. On the type bar there are projections 12 and 14 whichcorrespond in alignment to the two hammers 12 and 14 in FIG. 3, which inthat figure are shown as having been actuated by a particular symbol.When the type bar strikes the ribbon it prints one or more rectangles ofthe particular photoluminescent materials, in the case of FIG. 4 thosefrom strips 2 and 4.

FIG. 5 shows a series of strips 17 to 20 for the first four symbols ofthe message. The rectangles are numbered 21 to 26 respectively in thesame order, vertically, as the strips 1 to 6 of the ribbon and thehammers or projections 11 to 16.

In FIGS. 3 to 5, the size of the hammers or projections and therectangles is enormously exaggerated for the sake of clarity. In anactual machine the rectangles are quite tiny, for example having heightsof less than and of course the actual areas printed may be of anydesired shape, such as dots, as it is an advantage of the presentinvention that the particular shape of symbols is immaterial.

Reference has been made above to the possibility of combining thephotoluminescent or light-determined symbols with an ordinary coloredsymbol on the face of the type bar 10. Assuming that the four symbols ofFIG. 5 stand for the four letters C, O, S, T respectively, these letterscan be printed by a separate portion of a bar below the luminescentsymbols and this is shown also in FIG. 5. As the actuation of theseordinary type keys is conventional, they have not been shown in FIGS. 3and 4. The ordinary type keys require an additional strip on the ribbon,which is shown in dashed lines at 27 on FIG. 2.

FIG. 6 illustrates the readout and to illustrate this a symbol withrectangles in each of the strips, i.e., with rectangles 21 to 26, isshown. The symbol is irradiated with ultraviolet light, which is showndiagrammatically by the similarly labelled arrows in FIG. 6. This causesthe different rectangles 21 to 26 to fluoresce at their particularwavelengths or more accurately narrow wavelength bands. This isindicated on FIG. 6 by M to A As is often done, the wavelength symbol isused for a restricted range of wavelengths, for of course absolutefluorescent monochromaticity is an unrealizable ideal. The sixfluorescent beams are focused preferably by a cylindrical lens 28, onthe slit 29 of a spectrum analyzer 30, the output of which appears onconventional readout means 31. As the design of the spectrum analyzer 30and readout 31 are completely conventional and are not changed by thepresent invention, they are shown only diagrammatically as blocks. Itmay be mentioned that the spectrum analyzer may be of various types,such as an array of detectors with sharp cutting interference filters, aprism, or other dispersing means which separates the differentwavelengths geometrically and the like. The readout means may print thesymbols, represent them on a long persistent phosphor oscilloscope orany other type.

I claim:

1. A system of coded ink printing with photoluminescent codingcomponents including an apparatus having a keyboard, a ribbon with aplurality of strips each strip carrying an ink having a single codecomponent and being incapable of mixing with the ink on adjacent strips,type keys including vertically separated printing elements oriented tostrike the ribbon strips corresponding to a code for the particular typekey whereby discrete areas are in separate coding components withoutmixing of more than one component in a discrete area.

2. A system according to claim 1 in which the ribbon is provided with atleast one strip having an ink in a visible color.

3. A system according to claim 1 including means for readout comprisingmeans for illuminating with ultraviolet light the whole of the markingarea having the code marks at a single time and means for selectivelydetecting the different photoluminescent wavelength bands and readingout therefrom the symbol.

References Cited UNITED STATES PATENTS 855,559 6/1907 Chapin 197-1721,864,088 6/1932 Morton 178-28 XR 2,788,879 4/1957 Rand 197-172 XRConrad 178-30 XR Gutman 197-172 Brainerd 235-61115 Burkhardt et a1.235-61115 X Newing 252-3012 X Halverson 252-3013 Chaimowicz 235-61.114

U.S. C1. X.R.

